Anti-tumor effect of polysaccharides isolated from Taraxacum mongolicum   Hand-Mazz on MCF-7 human breast cancer cells

Purpose: To optimize the extraction conditions for the ultrasound-assisted extraction of polysaccharides from T. mongolicum (PTM) and investigate their anti-tumor effect on human breast cancer MCF-7 cells.
Methods: To optimize the extraction conditions of PTM, response surface methodology (RSM) was performed. The effects of extraction temperature, liquid-solid ratio and extraction time on the yield of PTM were investigated using a Box-Behnken design (BBD). The in vitro anti-tumor effect of PTM on MCF-7 cells was investigated by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay, while the mechanism of PTM-induced apoptosis was assessed by evaluating the expressions of p53, Bax and Bcl-2 proteins using western blot analysis. Furthermore, the in vivo anti-tumor effect of PTM on MCF-7 cells was studied in mice.
Results: The optimal conditions for the extraction of PTM were as follows: extraction temperature, 58.2 °C; liquid-solid ratio, 15 mL/g; and extraction time, 44.12 min. Under these optimal conditions, the yield of PTM was 4.84 ± 0.13 %. PTM showed significant anti-tumor effect on MCF-7 cells in vitro. The expressions of pro-apoptotic proteins, p53 and Bax, were significantly upregulated (p < 0.05), while the expression of anti-apoptotic protein, Bcl-2, was significantly down-regulated (p < 0.05) after treatment with PTM. PTM also showed significant inhibitory effect (p < 0.05) on MCF-7 cells in vivo in a dose-dependent manner.
Conclusion: RSM is effective in optimizing the extraction conditions of PTM by ultrasonic extraction. PTM possesses significant anti-tumor effect on MCF-7 human breast cancer cells, both in vitro and in vivo.

Keywords
Polysaccharides; Taraxacum mongolicum; Human breast cancer; MCF-7 cells; Apoptosis; Box-Behnken design; Response surface methodology